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  • #46
    Two early ones. Click image for larger version

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    'Man Invented time, Cyma Perfected it.'


    • #47

      If I were to show these two watches to a watch muggle and tell him that this is some kind of a pairing, he would surely register a confused expression ...But none of you are watch muggles, so hope to keep the explanation short ...Yes, at first glance, these two have little in common, apart from them being both Citizen diver’s watch and share the Promaster logo—big deal. Well, the relation is more than skin deep, so let’s have a look at what could make the Citizen Professional Diver’s 1000m Titanium (NH6931-06E “Auto-Zilla”) and the Citizen Promaster Marine Automatic Diver’s 200m Titanium (NY0070-83L) a potential nice pair.

      One rather obvious similarity is the “AUTOMATIC” on the dials of both divers. Those here who are dive watch enthusiasts would already guess that both run the Citizen Miyota Cal 8203, the standard fare for sometime when it comes to Citizen Automatic ISO-compliant, or true divers, i.e. those with the word “DIVER’S” on the dial. Most people in the watch communities usually view the 8203 dismissively—common, basic, cheap, no hacking that people seem to like, and seen too often inside no-name brands (yes, that includes the micro ones). While I won’t say that these people are wrong, I am in the small minority that happens to include quite a few highly experienced watchmakers I've met or corresponded with, who have great respect for the Citizen Miyota 8200 Series.

      With the Miyota 8200, you have probably the longest movement production run among all current self-winding calibres—now in its 45th year of continuous production. The modern Citizen 82xx is virtually unchanged from its original 1975 design, a testament to the level of engineering at the time in perfectly balancing performance, precision, and durability with economy of production. The 8200, of which the Cal 8203 is the flagship of, is a living horological history, and one that has not only served Citizen well, but brought life to many small independent brands that many enthusiasts love. All of this within reach of most people, and even more affordable in secondhand Citizen automatics.

      While the movement in both are not identical—the 1000m Auto-Zilla is equipped with the slightly better execution 8203B—the difference there is minor. Both watches are titanium, and this aspect is important because the world’s first watch with a solid titanium case was introduced in 1970 by none other than Citizen (X-8 Chronometer). Citizen made the first solid titanium watch—don’t let any Swiss company whose name begin with “I” tell you otherwise ...However, this similarity in case material is also a major difference between the two watches.

      To explain what sets them apart, we need to dive into surface hardness, the unit of measure of which is Vickers (Hv). The higher the value, the more resistant the surface is to scratches, with diamond having a hardness value of 7,100 Hv. Stainless steel (AISI 316L) has a hardness of approximately 220 Hv, which is actually a little harder than untreated/uncoated titanium. A bit harder than SS is Seiko’s proprietary Brightz Titanium (~300 Hv) and DiaShield (~500 Hv), used on watches like the current SBDX023 / SLA021 (

      The 200m NY0070-83L has a case made of Citizen’s proprietary SuperTitanium (Titanium + IP surface treatment), giving its surface a hardness of around 1,000-1,200 Hv. In comparison, 1,200 Hv is the same hardness as Sinn’s surface hardened “tegimented” steel. In some market regions, Citizen puts SuperTitanium as a sub-category of their proprietary Duratec, but if so, it is the softest type of Duratec. On the 1000m Auto-Zilla, the "Duratec" inscribed on the case back refers to Duratec MRK (1,300-1,500 Hv), which is about the same level of hardness as Sinn’s tegimented and Damasko’s surface-hardened U-boat steel. However, unlike the Germans, Citizen Duratec does not stop there—their “Duratect α” sits in the range of 2,000-2,500 Hv, as hard to scratch as sapphire crystal.

      Again in comparison, titanium nitride (TiN) that we see, gold-tone, on the case back of, say, the Seiko Golden Tuna, has a Vickers hardness of around 2,000 Hv.

      For me personally, these two Promaster divers showcases two major contributions that Citizen has made to the watch world.
      Last edited by Don; 21-02-20, 00:13.
      On the instruments we entrust to pace our lives, to bear witness to our days, and to be the keepers of the most precious thing we have... time.


      • cyma
        cyma commented
        Editing a comment
        Great write up as ususal Don, im a fan of Citizens, like Seiko have a vast choice to hunt for and pick up a goodie out of the 100s of models, then the fun of finding parts and getting it back working again,,lov it . LOL

      • Don
        Don commented
        Editing a comment
        Thank you, Pete. Citizen is certainly among my favourite brands, and the way I feel towards Citizen shines a positive light on brands that Citizen now own. I feel they have done great things for Bulova over the last 12 years, and believe that the future will be bright for both Frédérique Constant and Alpina, acquired by Citizen four years ago.